This invention relates to a process for production of 2,2-bis(4'-hydroxyphenyl)propanes used as starting materials for production of polycarbonate resins and epoxy resins and more particularly it relates to a process for production of 2,2-bis(4'-hydroxyphenyl)propanes by reacting a phenol compound with, for example, an unsaturated carbon compound in the presence of hydrochloric acid.
For production of 2,2-bis(4'-hydroxyphenyl)propanes (sometimes referred to as "bisphenol A" hereinafter), there have been known a process comprising condensing a phenol with acetone in the presence of an ion exchange resin (cf. Japanese patent examined publication No. 981/62), a process comprising reacting a phenol with an aliphatic unsaturated hydrocarbon represented by the general formula C.sub.3 H.sub.4 in the presence of, for example, Lewis acid such as boron trifluoride or aluminum trichloride or sulfuric acid (U.S. Pat. No. 2,884,462), etc.
However, the process using ion exchange resin has the problems that since water which is a reaction by-product reduces the activity of the ion exchange resin, yield of bisphenol A gradually decreases when reaction is carried out continuously for a long period of time. On the other hand, the process using Lewis acid or sulfuric acid as a catalyst (U.S. Pat. No. 2,884,462) has also problems, in addition to low selectivity of bisphenol (68%), that the treatment is complicated because the Lewis acid as catalyst must be deactivated and removed by neutralization of the Lewis acid in order to obtain bisphenols of high purity. Furthermore, in this process the deactivated and removed Lewis acid cannot be repeatedly used as catalyst and hence cost of catalyst is high.